MR imaging of coronary artery atherosclerosis in a porcine model

Heart,

Lung

and Circulation

2000; 9

48th Annual

NONINVASIVE IN VZVO MRI DOCUMENTS ARTERIAL REMODELING IN A NOVEL WHHL RABBIT MODEL. Xi l!Calhkv*. AG Zimuin G Helft.yadFuster., Cardiovascular Centre, Monash Medical Centre, Clayton, VIC, 3 168, and the Cardiovascular Institute, Mount Sinai School of Medicine, New York, NY, 10029-6574. Noninvasive MRI has the potential for serial monitoring of atherosclerosis progression. The WHHL rabbit is biologically preferable to cholesterol fed rabbit models of atherosclerosis as it more closely approximates humans. We studied an abdominal aortic balloon injury in the WHHL rabbit and undertook MRI before and 6 months post-injury. WHHL rabbits (age 3 months, n=l2), underwent MRI of the abdominal aorta in a clinical 1.5T system. Fast spin echo sequences were obtained with in-plane resolution of 350~ and slice thickness 3mm. T2W (TRiTE 2300/60 msec) and PDW (TRTE 2300115) were acquired. Sequential MRI studies were performed at baseline and 6 months later. After the baseline MRI balloon denudation was performed. The MR images of the same aortic sections (n=lO per rabbit) were compared at the two time points. A subgroup of rabbits (n=3) were sacrificed for histopathological correlation with MRI at this 6 month time point. High quality MR images were obtained. The mean vessel wall area for all MR images of aortic segments significantly increased (pcO.0001 paired students t-test) from 3.61M.68mm2 to 5.57ti.86mm2. Analysis of the luminal area showed that despite the increase in atherosclerotic burden over time, there was a slight but significant (p=O.O06) increase in the mean lumen area, from 4.36?1.46mm2 to 4.89+1.09mm2. A significant (p
THE IMPACT IMAGING ON.

OF ACUTE TECHNETIUTbl99M SESTAMIBI CLINICAL MANAGEMENT ALGORITHMS. C.R.Baldey(-). P.A.Qrmz&#l. L E.Gnee( A wetter C-2 (#) Emergency Department, (-) ‘Department of Nuclear Medicine, (^) Department of Cardiology. Royal Melbourne Hospital, Parkville, Victoria, Australia. To assess whether the known high sensitivity and specificity of Technetium99m sestamibi (MIBI) scintigraphy, during acute chest pain, will lead to an alteration in clinical management (nix.). Consecutive patients (pts.), n=120, were injected with 22mCi of MIBI during pain; SPECT imaging was performed 1 - 6 hours later. The population included inpatients and those presenting to the Emergency Department with chest pain deemed to be of intermediate risk for myocardial ischaemia. A questionnaire was completed by the requesting physictan prior to the study indicating the likelihood of cardiac disease and the proposed mx. if MIBI had not been available. For pts. already admitted to a ward an additional question regarding angiography (A) was asked. Follow-up mx. was evaluated from medical records.

Actual MX.

Discharge Ward C.C.U.

Discharge 19 5 2

Proposed Mx. Ward C.C.U. 32 6 16 12 15

P
13

There was a 33% reduction in total admissions and 59% of planned C.C.U. admissions. Conversely 7 pts. had discharge cancelled and 17 pts. required C.C.U. purely because of an abnormal MIBI. Also, of 39 pts. assessed for A 10115 had A averted while 4/24 undenuent A (3 with significant disease) purely because of the MIBI result. In our population, acute MIBI reduced total admissions by 33% and A by 40%. This may result in more appropriate triage of individual pts. in the mx. algorithm and potential cost savings.

PROGNOSTIC 3088 PATIENTS: KC

Sydney

Scientific

Meeting

IMPACT OF MYOCARDIAL A META-ANALYSIS

and Tufts New England

itch Medical Center,

of CSANZ

A127

VIABILITY

TESTING

IN

Boston

Concord Hospital MA, USA.

To examine the effects of treatment strategy (revascularization:REV vs medical therapy:-MED) on clinical outcomes in patients with coronary artery disease and left ventricular dysfunction following myocardial viability testing. METHODS: A literature search identified 24 viability studies (TI-201, FDG or echo) reporting late patient outcomes. Annual rates of cardiac death and nonfatal events (infarction, heart failure, unstable angina) were extracted from the papers and pooled data meta-analyzed using a random effects model. RESULTS: There were 3088 patients, 2164 men, ejection fraction 32+8% follow up 25zlOmths. 35% underwent REV, 65% MED. In patients with viability REV was associated with an almost 80% relative reduction in death (16% to 3.2%, chi-square 147, p
I

I,

MR IMAGING OF CORONARY ARTERY ATHEROSCLEROSIS IN A PORCINE MODEL. SG Worthlev*. G Hel3,AGmsm Favad. JT Fallon. JJ Ba&m~& Cardiovascular Centre, Monash Medical Centre, Clayton, VIC, 3168, and the Cardiovascular Institute, Mount Sinai School of Medicine, New York, NY, 10029-6574. Atherosclerotic plaque composition is central in the pathogenesis of acute coronary syndromes. Thus, there is a need for accurate imaging and characterization of atherosclerotic lesions. We describe the results of ex vivo and in vivo atherosclerotic plaque imaging in porcine models of coronary and aortic atherosclerosis. Complex coronary and aortic atherosclerotic lesions were induced by a combination of cholesterol feeding and balloon injury in Yucatan micro-swine (n=4). EX viva MR imaging was performed on the excised aortas and coronary arteries (left in situ on the heart). Tl W, T2W and PDW images were obtained. MR imaging accurately identified the plaque components (including calcified, lipid rich, hematoma&hrombus and fibrous components) as compared with histopathology. Mean wall thickness for the coronary arteries (1=0.94, slope=0.81) and aortas (1=0.94, slope=O.U) was accurately determined by ex vivo MR imaging (p